Last night I saw, on TV, an analysis by Aryeh Deri and Tzippi Chutbaru — a woman who participated in Dan Margalit’s show — of the Shai Daromi incident, based on Halacha and Rashi’s commentary. They claimed that Daromi’s actions were to be classified as self-defense. I would be happy to hear another opinion on the issue and more information.
I do not know enough of the in-depth details of the incident, but I will present you with the principles of Jewish law (Halacha) on this topic.
You must remember two things:
1. Halacha was determined based on the norms of ancient society (in Babylon and in Eretz Israel).
2. Halacha relates to Jews only. There is a separate law for one who is not a Jew, and one who kills him is not punished by a rabbinic court. (See the essay Gentiles in Halacha.)
Now we will clarify the Halacha. The law for one who comes to steal from another’s home appears as far back as the Scriptures. “When a man steals an ox or a sheep, and slaughters it or sells it, he shall pay five oxen for the ox, and four sheep for the sheep. If the thief is seized while tunneling, and he is beaten to death, there is no bloodguilt in his case. [One who kills him is not considered a murderer, but rather to have acted in self-defense.]” (Exodus 21:37-22:1). The Babylonian Talmud (Sanhedrin 72a) explains the reason (why one who kills a thief is not considered a murderer): Since the societal norm (at least in those days) was that a person worries about his money and so kills the thief, and since the thief knows this normative fact and even so breaks in to steal, it is reasonable to suppose that he is also ready to kill the owner if discovered. Since Jewish law rules that “If one comes to kill you, rise up to kill him first,” that one’s own life comes before the life of the thief, this is legitimate self-defense.
Using this assumption (that the law permits killing a thief only because it is likely that he would kill you if discovered), one may conclude that if this is not the reality, then one who kills a thief is considered a murderer.
The practical Halachic ruling is that if the owner is sure that the thief does not mean to kill him, only to take property, one is forbidden to kill the thief. If he does kill the thief, he is a murderer. Therefore, if the thief enters his field, garden, or sheepfold (or his home) to steal property only, one who kills him is judged to be a murderer, and this is also the case if the thief has completed his act of robbery and while he is leaving is killed (Maimonides, Laws of Theft 9:10-12).
N.B. I hope that modern civil law treats Jews and non-Jews equally (because in my heart I have a feeling that Jews have itchier trigger fingers when faced with Arabs).